Patent Literature 1, for example, discloses a driving assistance device as a driver dangerous driving reporting device. A vehicle interior camera and a driver state determination unit of this driving assistance device capture an image of the driver's head and determine the driver's line of sight, while a vehicle exterior camera and a danger determination unit (a danger direction determination unit) of the driving assistance device capture an image of the host vehicle's periphery and determine a direction relative to the host vehicle that is a danger factor. In Patent Literature 1, an assistance content deciding unit of the driving assistance device decides the content of a warning that reports the presence of a danger factor on the basis of the driver's line of sight (the output from the driver state determination unit) and the direction relative to the host vehicle that is a danger factor (the output from the danger determination unit). Specifically, warnings relating to danger factors outside of the driver's field of view are prioritized over warnings relating to danger factors within the driver's field of view. Thus, the assistance content deciding unit must determine whether or not a danger factor is outside of the driver's field of view.
However, for the assistance content deciding unit to make the determination described above, the output from the driver state determination unit (the vehicle interior image) and the output from the danger determination unit (the vehicle exterior image) must be synchronized, as shall be apparent. In other words, the image of the driver's head captured by the vehicle interior camera (the vehicle interior image) and the image of the host vehicle's periphery captured by the vehicle exterior camera (the vehicle exterior image) must be managed separately.
Because these two images are processed separately by the driver state determination unit and the danger direction determination unit, two directions (the driver's line of sight and the direction relative to the host vehicle that is a danger factor) must be determined and the assistance content deciding unit must determine whether or not the danger factor is outside of the driver's field of view on the basis of these two directions. In other words, a large processing load is involved when deciding the content of the warning that reports the presence of a danger factor.